In interfacing fiber for optical transmission such as at splices and taps, it is essential that transmission loss at these interfaces be kept to a minimum. The major cause of transmission loss is due to the condition and alignment of the end faces of the optical fibers to be connected.
It is highly desirable to prepare an optical fiber end face to have a smooth mirror-type finish, thereby providing a greater optical transmission area across the end face. In addition, it is also desirable to provide a fiber end face which is nearly perpendicular to the longitudinal axis of the fiber. The latter is particularly important where the connection device is of the type shown and described in copending, commonly assigned application, U.S. Ser. No. 06/126,887 filed on Mar. 3, 1980, now U.S. Pat. No. 4,378,145 and entitled "Method and Apparatus for Joining Optical Elements." This type of connection device includes a series of spheres arranged to form an interstitial opening less than the fiber diameter. Thus, opposing fiber end faces abut against axially spaced-apart surfaces on the spheres. Perpendicular end faces of the fiber would insure axial alignment of the fiber in this type of connection device, and thereby enhance optical transmission. Without such perpendicularity, the fiber end faces will be relatively skewed and optical transmission will be impaired.
Optical cleaving tools are known in the art for forming connection end faces. Typically, these devices include a scoring blade which is brought into contact with the fiber to score or nick the fiber surface. About this scored point the fiber can be separated. One manner of separating the fiber is shown and described in U.S. Pat. No. 4,202,475 issued May 13, 1980 to Harai et al, wherein the fiber is moved toward the scoring blade and then bent or flexed about the scored point to effect a sever. This bending or flexing about the scored point reduces the velocity of the crack propagation through the fiber and provides an optical end face with an increased mirror zone in which optical transmission is maximized. However, while providing an increased mirror zone, bending the fiber about the scored region will not always provide a perpendicular end face.
It is also known to apply a circumferential score around the surface of an optical fiber and then to apply an opposite axial tensile force to the fiber about the scored area. Such a device is shown and described in U.S. Pat. No. 4,216,004 issued Aug. 5, 1982 to Brehm et al. While providing a more suitable perpendicular end face, the application of pure axial tension tends to provide a misty end face reducing thereby optical transmission. Also where full circumferential scoring is required, more precision and structural complexity is necessitated.
It is desirable to provide an optical fiber cleaving tool which will cleave a fiber and leave a fiber end face which is both substantially perpendicular to the axis of the fiber and has a sufficiently large mirror zone to facilitate suitable interconnection.